Manual drive

Abstract

The invention relates to a manual drive for step-by-step operation, without any power, of a tap changer ( 1 ) on a tap-changing transformer. The manual drive has a position indication wheel ( 4 ) which is used not only, in conjunction with a pointer ( 15 ), for actual position indication, but at the same time as a component of mechanical final-position limiting ( 10, 11, 12 ). It can also furthermore be used ( 18 ) in a particularly advantageous manner as a component of electrical switching monitoring.

The invention claimed is: 
     
       1. In a manual drive for stepped, power-free actuation of a tap changer at a tapped transformer, wherein an insertable hand crank engages in a hand shaft and acts on a load transmission for actuation of the tap changer as well as an indicator transmission connected with a setting indicator, the improvement wherein
 the indicator transmission ( 3 ) comprises a setting indicator wheel, 
 the indicator transmission is so dimensioned that, with each complete actuation of the manual drive switching between two adjacent positions of the tap changer, the setting indicator wheel rotates through a defined angle, 
 the manual drive further comprises a fixed spring suspension at which a spring is pivoted, the spring being pivoted at its other free end to a trigger plate which in turn acts on a rotatable blocking fork shaft to which a blocking fork is fastened, 
 the trigger plate is so arranged that it is hit by trigger pins located on the setting indicator wheel as the trigger pins are moved past and is laterally deflected, 
 the hand shaft has a mechanical end abutment, 
 the deflectable blocking fork so cooperates with the end abutment that the blocking fork in deflected state on reaching an end setting mechanically engages in the end abutment, 
 a pointer co-operating with a scale is fixedly arranged at the setting indicator wheel, 
 the setting indicator wheel has on a concentric circle seat bores for reception of the trigger pins that are arranged relative to one another at an angle corresponding with the rotational angle of the setting indicator wheel for a switching over, and 
 the trigger pins are so detachably securable at selected bores of the setting indicator wheel that the manual drive is adaptable to different numbers of possible switch settings of the tap changer and to different revolution numbers of the hand crank for one switching over. 
 
     
     
       2. The manual drive according to  claim 1 , wherein the setting indicator wheel has, on a further concentric circle, further seat bores having the same pitch as the bores for the trigger pins and that fastened in the seat bores is a switch monitoring segment having cams that cooperate with at least one electrical switch.